<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .bg {
            color: red;
        }
    </style>
    <!-- <script src="https://cdn.bootcdn.net/ajax/libs/vue/2.6.11/vue.min.js"></script> -->
    <script src="https://cdn.jsdelivr.net/npm/vue@2.6.11"></script>
</head>

<body>
    <div class="app">
        <div class="bg">
            Hello World!!!
            {{msg}}
        </div>
        <div class="bg">
            {{msg}}
        </div>
    </div>
    <script>
        new Vue({
            el: '.app',
            data: {
                msg: 'Hello Vue!!!'
            }
        })
    </script>
</body>

</html>